Blades or vanes for gas turbines, which are used in the compressor part or turbine part as guide vanes or rotor blades, are usually produced as one part by forging or investment casting. This also applies in particular to blades or vanes which have a platform and/or a shroud segment.
The loading of guide vanes and rotor blades in the gas turbine is increased by the continuously encouraged increase in the hot gas temperature and the reduction of the cooling air consumption. It is therefore desirable to reduce stresses which arise on the blades or vanes by design measures. Components which experience reduced levels of stress can withstand higher temperatures with the same service life. In this way, it is possible to accommodate for the demand for a higher hot gas temperature and a lower cooling air consumption.
EP 2 189 626 A1 discloses a rotor blade arrangement for a gas turbine, which rotor blade arrangement can be fastened to a blade carrier and comprises in each case a main blade part element and a platform element, wherein the platform elements of a blade row form a continuous inner shroud. A reduced level of stress is achieved therein by virtue of the fact that the blade airfoil element and the platform element are formed as separate elements and can each be fastened to the blade carrier separately. A disadvantage of this solution is that it is not suitable for retrofit tasks, because the nature of the fastening to the rotor changes by virtue of the platform element, and therefore the rotor itself has to be adapted.
U.S. Pat. No. 7,762,781 B1 discloses an arrangement made up of a turbine blade or vane and a platform, in which the platform is formed as a separate element which is fastened to the blade or vane by special pins. This solution has the disadvantage that the individual elements are very expensive to produce.